含缺陷压铸AlSi ₉ Cu ₃ 合金疲劳寿命的计算

The study on correlations between casting defects and fatigue life in AlSi ₉ Cu ₃ pressure die-casting aluminum alloys might help to the prediction of aluminum alloys fatigue life, possessing an important practical value. The fatigue life of aluminum alloys with defects could be calculated by Paris'law. However, the effect of defect types on alloys fatigue life was overlooked in past studies, which resulted in the reduction of calculation accuracy. In this paper, on the basis of research on fatigue life of die-cast aluminum alloy with different defects, Paris'lawwas modified by introducing geometric factors of different defect types, improving its calculation accuracy. Firstly, we explicated that alloys consisted of through crack, surface crack and corner crack by analyzing the results of fatigue test. Secondly, the average geometric factors of 1.421, 0.814 and 0.947 were calculated for through crack, surface crack and corner crack, respectively, where through crack showed the greatest influence on fatigue life among three cracks. On this base, fatigue life of aluminum alloys was calculated by Paris-Erdogan formula, where the calculated results could correspond well to test data and the error was between half and twice of calculated fatigue life, confirming the reasonability of hypothesis and feasibility of calculation. This calculation could provide important theoretical basis and practical reference for the prediction of aluminum alloys fatigue life in practical applications.